Lifting magnet



' July l2, 1949.

J. D. LEITCH LIFTING MAGNET Filed'July 15, 1945 5 Sheets-Sheet 2,Y////////// ffl 1N VEN TOR.

BYJOHN 0. l ,5/ TcH l Zio( my. M

AT1-ORNE K5 July 12, 1949. J. D. ElTcH 2,476,049

LIFTING MAGNET NVENTOR.

a/oH/v D. E/TcH /4-7 ro fiM/E V5 Patenfed July 12, 1949 2,476,049

Company, Clev'el'and, Oh'io; a" corporation" of OhfU" vantig'e" .0fWODIdl Il@ fili' replacementVY of the bottom of the container. The outermarginal portion of the flange is fastened to the outer pole piece ofthe magnet frame by a continuous annular weld and the inner bottom edgeportion of the container is fastened to the inner pole piece by acontinuous annular weld. The provision of the peripheral flange permitsthe outer side wall portion of the coil container to be made of thinsheet metal welded to the top and bottom members of the container sincethe large weld provided to secure the coil container to the magnet frameis spaced from the side wall by the width of the flange and thus theheat therefrom does not adversely affect the side wall portion or thewelded connection between the side wall portion and the bottom of thecontainer. Since all of the welds are annular and coaxial with theframe, to remove the coil from the annular groove or channel in theframe, it is only necessary to machine out annular welds, which can bedone by machine tools that are generally available and by a singlecentering of the magnet in the machine. The winding in a preferredembodiment is prevented from rotating relative to the enclosure by thecombined action of frictional forces between the winding and the top andbottom walls of the enclosure and by adhesive properties of insulatingmaterial within the container.

It is an object of this invention to provide an improved lifting magnetof the circular type.

Another object is to provide a lifting magnet having the foregoingadvantages, and in which the foregoing disadvantages are eliminated.

Still another object is to provide an improved winding construction fora circular lifting magnet.

Further objects are to provide an improved lifting magnet of thecircular type having a hermetically sealed coil unit separate from themagnet frame, torprovide a lifting magnet having a hermetically sealedcoil enclosure welded to the magnet frame, to provide a hermeticallysealed coil enclosure for a circular lifting magnet having an externalperipheral fiange portion for use in welding the enclosure to the magnetframe, to provide an improved terminal box construction for a liftingmagnet, to provide improved means for preventing rotation of -a windinginsulated from and sealed within a metallic enclosure, and to provide animproved terminal lead construction for a lifting magnet.

Other objects and advantages will become apparent from the followingdescription wherein reference is made to the drawings, in which Fig. 1is a top plan view of the magnet;

Fig. 2 is an enlarged diametrcal sectional view taken generally alongthe line 2 2 of Fig. 1;

Fig. 3 is a relatively enlarged fragmentary top plan view of a portionof the coil assembly;

Figs. 4 and 5 are sectional views taken generally along lines 4 4 and 55, respectively, of Fig. 3;

Fig. 6 is a fragmentary diametrcal sectional view taken generally asindicated at 6 6 in Fig. 1;

Fig. 7 is a fragmentary diametrcal sectional view of a portion of amodified magnet, and

Fig. 8 is a fragmentary sectional view taken generally along line 8 8 ofFig. '7 with parts omitted.

Referring principally to Fig. 2, the lifting magnet illustrated in thedrawings comprises a circular magnetic frame Hl having integraltherewith a cylindrical inner pole piece Il and an annular outer polepiece I2. The pole pieces il and l2 form downwardly projectingconcentric exte ions of the frame l and define an annular winding spacei4 therebetween which is open at the bottom to receive an annular coilunit to be described. The inner pole piece ll is in the form of a hollowcylinder with an axial opening I6 extending through the magnet framewhich opening has a lower frusto-conical portion Ilia and an uppercylindrical portion lb. A unitary inner or central pole shoe i8 has anupper integral portion Ia complementary to and tting snugly in intimateflux conducting relation with the surfaces of the opening IG and a lowerfiange-like portion lb provided with an annular shouldered recess 80 forreceiving an inner marginal portion of an annular non-magneticprotective plate 2l preferably formed of cast manganese steel. The poleshoe I3 has the usual axial opening I9 therethrough and is secured inposition by a means located entirely at the top of the magnet frame i3and preferably by a continuous annular welded connection 22 formed atthe outer marginal portion of the top surface of the pole shoe.

The outer marginal portion of the plate 2l is received in an annularshouldered recess 24a of an annular outer pole shoe 24 having anupwardly extending annular flange Zlib around its outer periphery whichfits into an annular shouldered recess I2a cut in the outer periphery ofthe outer pole piece I2 adjacent its lower face. A continuous weldedconnection 25 may be made between the pole shoe 24 and the pole piece l2along the top of the flange 24h to secure the pole shoe 24 in position.This welded connection 25 is annular and coaxial with the pole piece.

Because manganese steel is difficult to machine, provision has been madefor reducing to a minimum the amount of finishing required on the plate2l. To this end, concentric downwardly extending annular projections orridge portions 2 la and 2 lb are formed on the plate 2l and have theirlower face surfaces finished and in engagement with the outer marginalportions of horizontal finished surfaces 18d and 24e of the recesses itcand 24a, respectively. With the exception of the finished areas of theridges 21a and 2lb, the lower face surface of the plate 2| may be leftunfinished. The plate 2| is preferably of hollowed ribbed construction,as suggested in Fig. 2, to provide greater strength and rigidity forunit weight and to insure a sound casting. Clearance 26 is provided atthe top of the ribs so that finishing of the entire top surface of theplate 2l is not necessary. In order to further reduce the amount offinishing required on the top surface of the plate 2|, the inner andouter marginal portions thereof are provided with a plurality ofcircumferentially spaced raised areas or pads 2 lc which have their topsurfaces 2 Id finished thereby to provide concentric interrupted annularbearing areas for the coil unit, the surfaces 2|e between the pads beingleft unfinished.

Hoisting chains 23 are secured respectively as by pins 23a to aplurality of circumferentially spaced lugs 21 formed on the top of theframe I0. The lugs 2l extend to the outer peripheral edge of the frameand have respective openings 21a therein for receiving cables or thelike (not shown) for the purpose of exerting sidewise forces on themagnet when necessary.

So long as an annular winding space IB is provided, the specificarrangement of the pole shoes, protective plate, and the magnet frame isimmaterial to the present invention; the construction described forillustrative purposes is similar to that described and claimed in acopending patent application of D. C. Wright and A. L. Ward,

hermetically sealed, those having adhesive properties may be used hereininstead of the material above described.

The coil unit is received in the annular channel IIS with the bushings58 fitting into respective circumferentially spaced recesses |2b (Fig.2) formed on the outer pole piece l2. The annular welded connection 3|)between the weld 3|, the hub 28, and the inner pole piece secures thecoil unit to the inner pole piece and a continuous annular weldedconnection 6| formed at the outer peripheral edge 29h of the plate 29within a shouldered recess adjacent the lower face of the pole piece l2secures the coil unit to the outer pole piece |2. Since the weld 6| isspaced from the side Wall 5| by the width of the flange 29e, a largerand stronger weld can be made Without risk of deforming, overheating, orotherwise damaging the thin sheet metal of the wall 5| and the weldedconnection 55 when making the weld 6|.

The leads d5 and 46 extend in circumferential spaced relation through anopening E2 in the frame It) extending from the top of the annular recesslli and enter a terminal box 64 formed on the top of the frame. A tubeor sleeve 62' pressed into the opening 62 rests upon the insulator i9and the hub 28. The annular joint around the bottom of the sleeve G2 issealed from the inside of the sleeve by impregnated asbestos cord (notshown), and then the sleeve 62' is preferably filled with the materialGil which is allowed to polymerize without externally applied heat.

The terminal box 64 (Figs. 1 and 2) has end walls 84a and 64b, sidewalls 64e and 54d, and a central wall 64e dening two chambers 65 and'66. The upper end portions of the leads 45 and 11S are secured torespective circumferentially spaced terminal studs 68 which are receivedin respective spaced openings in the wall 64e, each of the studs 6Bbeing insulated from the wall 64e by a sleeve l2 and a spacer or collari4. Suitable gaskets 1 3 are provided to make a hermetic seal around thestuds S8. Circumferentially spaced openings i5 closed by respective pipeplugs 'i6 are provided in the wall 64a to permit drilling of theopenings in the wall 64e and manipulation of the magnet connections. Atop wall 64j of the terminal box 64 has a pair of threaded openingswhich are closed by plugs 'I8 and 19, respectively.

Leads 8G and 8| (Fig. 1) of a cable 82 are secured to the respectiveterminal studs 68 within the chamber 65 and pass through a suitable seal(not shown) in the side wall Md. The cable 82 is protected frommechanical abuse by a wall 85 extending outwardly from the wall 615e andhaving a portion extending in parallel spaced relation to the wall 64duntil it merges into one of the lugs 21. A lead clamp 3% is provided tosecure the cable 82 in position.

The modification of Figs. 7 and 8 provides means in addition to theadhesive and frictional forces of the principal embodiment for holdingthe winding against relative rotation with respect to its enclosure. inFigs. 7 and 8, pairs of vertically aligned and spaced U-shaped bracketsBil are secured, as by spot-welding, to the inner surface of the wallmember 5| at circumferentially spaced positions (only one pair beingshown). Opposite the pairs of brackets 953, the insulation plates 35a to35e, inclusive, are provided with respective notches 9| for receiving anelongated locking member S32 formed of insulating material.

An alternative method of winding the coil sections 32a, B2b, 32e. and32d is to be preferred when the locking members 92 are used. In thealternative method, the hub 28 and the plate 4| secured together by theWelded connection Ml constitute the spider upon which the coil sectionsare wound. After the coil winding operation, the members 92 are slippedinto position in the recesses 9| and then the bottom plate 29 is securedto the hub 28 by the welded connection 3|. The wall member 5l is thensecured to the plate 29 at one point and then progressively bent tocylindrical configuration and welded in place by the welded connection55. A welded connection 94 (Fig. '7) is formed between the top edge ofthe wall member 5| and the outer peripheral edge or the plate 4|. Itwill be noted that before the welded connection 94 is made, the coilsections can be compressed and that since the upper portion of the wallmembers 5| overlaps the outer edge of the plate 4|, the verticaldimension of the plate 5| is not critical.

Thus the coils not only are hermetically sealed but also are fixed inposition circumferentially relative to the magnet frame. This isaccomplished (a) by securing the coils in fixed position in thehermetically sealed container either by a combination of frictionalforces due to the axial compressive stresses on the coils with theadhesive forces due to the insulating material which is thermal settingand bonded to the coils and to the walls of the container or withmechanical interlocking of the coil insulation discs with the insulationstrips interlocked, in turn, with the container walls, and (b) byIsecuring the container, in turn, to the magnet frame by continuousannular welds coaxial with the frame. Since all of the welds are annularand coaxial, all can be removed easily for servicing or disassemblingthe magnet by centering of the magnet frame in a suitable rotary cuttingmachine and machining ofi the weld.

I claim:

1. A lifting magnet comprising a magnetic frame member havingconcentrically arranged inner and outer pole pieces extending downwardlytherefrom and dening an annular winding space therebetween, an annular,hermeticallysealed, coil-containing enclosure received in said windingspace, said enclosure comprising a relatively thick metal bottom wallportion and an outer cylindrical metal side wall portion, said bottomwall portion and said side wall portion being welded together, and saidbottom wall portion having an integral marginal portion extendingoutwardly from said side wall portion to define a ilange, and a Weldedconnection between the outer peripheral portion of said ilange and saidouter pole piece.

2. A.' lifting magnet comprising a magnetic frame member havingconcentrically arranged inner and outer pole pieces extending downwardlytherefrom and dening an annular winding space therebetween, an annular,hermetic-allysealed, coil-containing enclosure received in said windingspace, said enclosure comprising a relatively thick metal bottom wallportion and an outer cylindrical metal side wall portion of lessthickness than the bottom Wall portion, said bottom wall portion andsaid side wall portion being welded together, and said bottom wallportion having an integral marginal portion extending outwardly fromsaid side wall portion and transversely with respect to the axis of saidpole pieces to define a ilange, and a welded connection between theouter peripheral portion of said flange and said outer pole piece.

3'. ,a lifting magnet comprising a magnetic frame member having,coil-centinela arranged inner and einer noie nieces ,extending downardly therefrom and .donnine annular ding Space therebetween an emisionbermen allysealedl Gailreontainine .enclosure received vin said Windingspace, saisi .enclosure ,comprising .a relatively thick metal bottomwall portion and an outer cylindrical sidewall portion formed ofrelatively thin sheet metal, a continuous annular welded connectionbetween said `wall portions securing said'wall portions together with anintegral marginal portion of said bottom wall portion extendingoutwardly from said side wall to dene a flange, and a Welded connectionbetween the outer marginal portion of said flange and the inner marginalportion of said outer pole piece, whereby said last named weldedconnection can be made without effect on said rst named weldedconnection or on said sidc wall portion.

4. An annular, hermetically-sealed coil unit for reception into anannular groove in the lower face of a circular lifting magnet frame,comprising an annular metal container having a tubular hub portion andan outer cylindrical side Wall portion joined by planular top and bottommembers, a winding wound upon said hub portion between said top andbottom members, said winding when uncompressed being of greaterthickness than the normal distance between said top and bottom membersand being held in compressed condition by and between said top andbottom members thereby to cause frictional forces which oppose relativerotation between portions of said Winding and between said winding andsaid container.

5. An annular hermetically-sealed coil unit for reception into anannular groove in the lower face of a circular lifting magnet frame,comprising an annular metal container having a tubular hub portion andan outer annular side wall portion joined by planular top and bottomwall members, a winding wound upon said hub portion between said top andbottom members, said winding when uncompressed being of greaterthickness than the normal distance between said top and bottom membersand being `compressed by said top and bottom members thereby to causefrictional forces which oppose relative rotation between said windingand said container, said winding further being of lesser diameter thanthe inside diameter of said side wall portion thereby to dene an annularspace within and at the outer marginal portion of said container, andinsulating material within said space and having the property ofadhering to said winding and to said walls thereby opposing relativerotation between said container and said winding.

6. In a circular lifting magnet frame having a top surface slopingdownwardly and outwardly from the axis of the magnet, a terminal boxcomprising a closed chamber dened by four side walls cast integral withsaid frame and a portion of the frame forming the bottom wall, one ofsaid side walls of said box extending in the direction of said slope andhaving an opening for magnet leads, an integral wall extending laterallyoutwardly from said one side wall and positioned further from the axisthan said lead opening, a suspension lug on said magnet frame, saidoutwardly extending wall having a portion extending generally alongsideand spaced from said one wall and merging at its inner end with said lugthereby to provide a protective barrier for and exteriorly of saidopening.

7. A lifting magnet comprising a frame having l0 concentrically arrangedinner and outer pole pieces extending 'downwarf n Atherefrom andvderining a winding space therbetwnl'a'n opening between said space andthe tp'f'said'frameQa Cylindrical het resister Syrioiireins Said innerpole piece, an axially directed groove in said hub member V.facing saidwinding space, a multi-layered winding on said hub member, a terminallead vreceived in said groove and extending from the lowermprst layer ofsaid winding through said opening, and an elongated C-shaped insulatorreceived insaid groove and partially enclosing said lead.

8. In a lifting magnet, a frame having an annular groove in the lowerface, an annular, hermetically-sealed coil unit for reception in saidgroove and comprising an annular container having an inner cylindricalhub portion, an outer cylindrical side wall portion, and a winding woundupon said hub portion and of lesser diamcter than the inside diameter ofsaid side wall portion thereby to denne an annular space Within saidcontainer, and circumferentially spaced means in said space andmechanically interloclred with the winding and lwith said side wallportion :For opposing relative rotation of the winding and side wallportion.

9. In a lifting magnet, a frame having an nular groove in the lowerface, an annular, liermetically-sealed coil unit for reception in saidgroove and comprising an annular container havF ing an inner cylindricalhub portion, an outer cylindrical side wall portion, and a winding woundupon said hub portion and of lesser diamcter than the inside diameter ofsaid side wall portion thereby to define an annular space with-- in saidcontainer, said winding comprising a plu-- rality of axially spacedcoils and insulating discs therebetween and interlocked with theadjacent coils, and said discs being of greater diameter than the coilsand extending into said annular space, and circumferentially spacedmeans inW terlocking said discs and said side wall portion for opposingrelative rotation of said coils and side wall portion.

1G. In a lifting magnet, an annular, hermetically-sealed coil unit, amagnet frame having an annular groove in the lower face accornrnodati1ng said unit, said unit comprising an annular metal container having atubular hub portion and outer annular side wall portion joined byplanular top and bottom wall members, a winding Wound upon said hubportion between said top and bottom members, said winding whenuncompressed being of greater thickness than the nor-- mal distancebetween said top and bottom members and being compressed by said top andbottom members thereby to cause frictional forces which oppose relativerotation between said winding and said container, said Winding lurtherbeing of lesser diameter than the inside diameter of said side Wallportion, thereby to define an annular space Within and at the outermarginal portion of said container, insulating material within saidspace adhering to said windu ing and to said walls and thereby opposingrelative rotation between said container and said winding, and meansanchoring the container to the frame for opposing relative rotation ofthe container and the frame about the axis of the groove.

JOHN D. LEITCH.

(References on following page) l1 REFERENCES CITED Nlmllg The followingreferenloes are of record in the 133152530 file of this patent:1,813,976

UNITED STATES PATENTS 5 glll Number Nam'e Date 3791664 844,578 CavanaghFeb. 19, 1907 1,015,728 Eastwood Jan. 23, 1912 1,326,366 Milton Dec. 3o,1919 10 Number 1,334,504 Parker Mar. 23, 1920 135,265 1,455,199 GrotenMay 15, 1923 Na-me Date Myers July 3, 1928 Kurath July 28, 1931 GoffAug. 18, 1931 Hodgson Oct. 12, 1937 Miles May 3, 1938 Stanko July 3,1945 FOREIGN PATENTS Country Date Great Britain Sept. 7, 1922

